1. Field of the Invention
The invention relates to an improvement of a bonding apparatus, and, in particular, to a bonding apparatus including a bonding head having means for anti-oxidation of a semiconductor chip.
2. Description of the Related Art
Conventionally, with a bonding apparatus for thermally bonding a semiconductor chip onto a substrate, it is known that bonding defects may occur due to oxidation of a portion to be bonded in the semiconductor chip. In order to prevent the bonding defects, there has been employed shielding means for shielding the portion to be bonded with inert gas (including nitrogen gas, etc).
In such a bonding apparatus with the shielding means, in order to suppress the oxidation of the portion to be bonded in the semiconductor chip when thermally bonding the semiconductor chip onto the substrate, as shown in FIG. 5 of Japanese Patent No. 3455838, which shows a background art thereof, a hood is provided to a substrate supporting stage and the nitrogen gas is blown. However, in order to decrease oxygen concentration by blowing the nitrogen gas throughout the substrate supporting stage, considerable amount of the nitrogen gas may be required. Accordingly, in reality, it is difficult to reduce the oxygen concentration to the extent necessary to suppress the oxidation of the portion to be bonded in the semiconductor chip.
Therefore, as shown in FIG. 1 to FIG. 4 of Japanese Patent No. 3455838, a plurality of holes for supplying the inert gas are provided to the bottom face of the bonding head, and there is provided shielding means shielding the portion to be bonded in the semiconductor chip from the oxygen by supplying the inert gas through the supplying holes. In this shielding means, since the substrate and substrate supporting stage exist just under the shielding means during the bonding operation, this shielding means is effective during the bonding operation. However, in this shielding means, it is not possible to shield with the inert gas the portion to be bonded in the semiconductor chip during conveying the semiconductor chip using the bonding head and being ready to hold the semiconductor chip during such a conveying operation and being ready to hold the semiconductor chip. Accordingly, when conveying the semiconductor chip and being ready to hold the semiconductor chip, the oxidation of the portion to be bonded in the semiconductor chip may still occur.